selection of unit for transfusion

[sona]

hi all

if a blood unit is screened for all parameters and has negative results of serology and malarial parasite

and has hb%> 12g\dl

but it has increased bile OR abnormal cellular counts like wbcs and platelets

what will be your choice in this case should these units be discarded if yes WHY?

[heathervaught]

Sona - in the US, it is very unlikely that an abnormal cell count for WBCs or platelets would be discovered in the Whole Blood (WB) donor.

In the past, we have detected previously undiagnosed cases of Polycythemia vera in our Component Manfuacturing laboratory. These components would have a hct so high that a 500 mL collection would contain less than 200 mL of plasma. Recently, we changed methodologies for qualifying WB donors and now use the Hemacue device (measuring quantitative hemoglobin), and would defer a donor if their hemoglobing value was too high.

We currently leukoreduce prior to centrifugation, so we cannot detect elevated WBCs. Before we implemented this practice and centrifuged unleukoreduced WB, we would occasionally identify components that appeared to have a large "buffy" layer. We would identify one of the EDTA tubes that was being used for infectious disease testing and request that a WBC count be determined. I think one or two donors actually had a really high WBC count and was referred to their primary physician.

In both cases, the products were discarded at our medical director's discretion.

[rravkin@aol.com]

Heather,

I was curious to know of any advantages there were to leuko-reducing prior to centrifugation? Is it better to filter a less concentrated product? This makes sence.

[heathervaught]

There are a few advantages to leukoreducing whole blood, but I have found that most of them are process-related. Leukocyte reduction of either whole blood or packed red cells results in acceptable residual WBC counts and RBC recovery.

We did not study how "concentration" impacts filtration.

When leukoreducing packed red blood cells, you separate them from the plasma, create the non-leukoreduced product into the computer system, add the additive solution (if applicable), place the unit in a refrigerator, remove the product from the refrigerator to attach the filter, return the product to the refrigerator during filtration, remove the product from the refrigerator to document the product changing from non-leukoreduced to leukoreduced, return the product from the refrigerator, then remove the product from the refrigerator to detach the filter and make segments, then return the finished product to the refrigerator. A very labor-intensive process! You are allowed 3 days to complete filtration, and we often took every bit of those 3 days to get those products released and available to our hospital customers.

When we implemented a whole-blood filtration system, the filter is attached to the bag by our manufacturer. When the whole blood is received in the production laboratory, it is filtered at room temperature (within 8 hours of collection), the filter is removed, segments are made, the product is centrifuged, the RBCs are separated from the plasma, additive solution is added, and the finished product is stored in the refrigerator. We average 550 units collected every day, and now we have products available for our hospitals as soon as infectious disease testing is completed. It is a much more streamlined process.

The only real drawback to whole blood filtration is that plasma volume is lost. Since we only need about 20% of our plasma to meet our needs for transfuseable products and the rest is used for fractionation (manufacturing plasma-derived therapeutic products), losing plasma volume impacts the bottom line.